1. The problem statement, all variables and given/known data I am trying to determine the fractions of electrons with energy between E=2ev and E=3ev. to simplify the equation I have substituted everything out leaving an integral which is what I need help with. 2. Relevant equations f(x)=(Sqrt(x)*e^-x)dx -integrate from x=1 to x=1.5 -divide into 5 parts 3. The attempt at a solution After simplifying and factoring all constants the above equation is what I'm left with. I'm quite confused with this integral but was told by my professor to divide the interval into five equal segments and approximate the area under each rectangle. I remember doing something similar to this in a previous calc class involving riemann sums, whereby I belive the rectangles were also used, but I cannot seem to recall the necessary steps to solving this definite integral. Any ideas and suggestions would be great.